It is known that roller skates of the said type have support structures that are basically constituted by two parts which are mutually telescopically engaged by means, for example, of the sliding coupling of cooperating prismatic guide elements. It is also known that once the desired length of the skate has been set, the said two parts of the support structure are mutually fixed together by means of one or more nut and bolt combinations. In other cases and in order to increase the clamping force between the two parts when fixed together in their desired positions, it has been proposed to replace the nut of the nut and bolt combination by a suitably dimensioned transverse plate having fine teeth on one of its faces for engaging corresponding teeth formed in one of the parts of the skate structure.
These fixing systems although widely used and advantageous from several points of view, suffer from a drawback of a technical nature which has not been overcome until now. Thus, for example, during sports use it is well known that the skate is subject to considerable forces and particularly to strong and prolonged vibrations which can quickly lead to a permanent, or at least a dangerous, mutual disengagement of the fixing means. On the other hand, it is also easy to find the opposite situation arising in which the nut and bolt become locked together, for example, due to the formation of roughness in the coupling or due to deformation.
Moreover, the adjustment of the length of the skate is always laborious due to the manipulation of each nut and bolt combination, the tightening of which always requires the use of a suitable tool.
The main object of the present invention is to provide an extendible roller skate having a device for locking the skate structure at the desired length, with structural and functional characteristics such as to overcome completely the disadvantages mentioned above with reference to the known art.